Safety-valve.



H. G. MoGARTY. SAFETY VALVE. APPLICATION mm rms.21, 1908 910,71 1 Patented Jan. 26, 1909.

A awznkoz attowup THE mamas PETERS 5a., wnsnmcrmv, n. cy

HARRY O. McOARTY, OF WILLIAMSPORT, PENNSYLVANIA.

SAFE TY-VALVE.

Application filed Februaryl21, 1908.

Specification of Letters Patent.

Serial No. 417,145.

To all whom it may concern:

Be it known that I, HARRY C. McOAR'rY, a citizen of the United States of America, residing at Williamsport, Lycoming county, State of Pennsylvania, have invented certain new and useful Improvements in Safety- Valves, of which the following is a specification.

The present invention relates to a safety valve for steam boilers. It is of the kind commonly known as a pop safety valve.

In valves heretofore made under the Coale patents, No. 825,380, No. 855,431, and No. 657,086, it has been found that the large size valves have a tendency when discharged to rock in the case and strike the guides, producing an objectionable chattering sound and a destructive wear of the parts.

The resent invention is designed to overcome this defect and has successfully overcome it.

It consists of so constructing the valve as to give it a shallow concave outer surface and a convex inner surface. The cup form thus given the valve causes it to protrude through its seat into the pressure chamber. A shallow step is located in the center of the outer surface of the valve which, when the valve protrudes throu h the seat into the pressure chamber, will locate the foot of the springbearing block at the bottom of the valve cavity, and the pressure of the spring will be applied to the valve at a point on what may be called the pressure side of the seat. The spring bearing block is so constructed as to leave a free open space between it and the surface of the valve which will not fill and be sealed by sediment. The surface of the valve upon the pressure side by virtue of its sha e is 1provided with a steam deflecting sur 'ace w ich causes the impact of escaping steam to be less effective in its tendency to tilt or rock the valve. The usual guides on each side of the valve are also provided. These elements combine and cooperate to produce a valve which, even in large diameters, will not rock unduly or chatter in the case.

Various types of safety valve heretofore in use have employed valves in which the pressure surface was curved, concave or convex. In some cases the valve protruded through the seat. and the step of the spring bearing block was located at a point on the pressure side of the seat. Guides have also been used on both sides of the valve and of various shapes. But the defects of these various structures were found in the fact that the clearance between the spring bearing block and the valve was so small as to permit the accumulation of sediment therein and thus seal the bearing block to the valve and destroy the inde endence of the valve. In some cases this difficulty was avoided by providing a considerable clearance between the bearing block and the valve, but in those cases the step was at least as high as or beyond the seat 011 the exhaust side. In no structure of which I am aware has the combination ever been produced of a valve the body of which protruded through the seat and having an inclined or convex surface upon the pressure side, a step located upon the pressure side of the seat, and the bearing block and valve so constructed in relation to each other as to maintain a lar e clearance between them and the indepen ence of the valve; with means for guiding the valve so as to keep it in its center position. This com bination of features, all of which are in some degree old, is a new combination never be fore made and which produces a new and improved result in safety valves, that is to say, it permits the construction of large sized valves which will operate positively and without rocking or chattering under all kinds of conditions.

In the accompanying drawing, the figure is a vertical central section of a safety valve embodying the invention.

The valve casing or chamber (1) is secured by the usual screw connection to the container (2) for fluid under pressure, to which the casing is connected by a suitable opening. The casing consists of a lower section (3) substantially cylindrical in form and having its aXis in a vertical position. Its outer edge (4) is threaded upon the interior and it is provided upon its interior with a vertically projecting cylindrical flange, spaced from its outersurfaoe, upon the inner edge of which is the valve seat (8). outer cylindrical edge, screwed into the internal thread (4:) is an upper section of the casing (5), having its axis alined with that of the lower section and provided with a reduced threaded portion (6) upon its exterior adapted to engage with the thread (4) upon the lower section. The upper end of the in terior cylindrical flange of the lower section is provided with a circular inclined valve seat (8). The upper section of the casing Patented Jan. 2c, 1909. l

Mounted upon the above the valve seat is provided with a cylindrical guide 10, located over the valve seat and spaced from the outer wall of the casing (5), forming between the exterior wall of the casing (5) and the interior cylindrical guide (10) acircular chamber (11) whichterminates at its lower extremity in an opening above the valve seat and at its upper extremity in a muflier (12), which will be hereafter termed the inner muffler. This mufiler consists of the closed upper end of the chamber (11) perforated with holes (13) in its three sides. The upper section of the casing is also provided within the muffler with an integral vertical cylindrical extension (14) perforated at its upper end and of less diameter than the inner muffler (12), forming with other members to be described an inclosure known as the spring chamber. The whole upper portion of the casing including the inner muffler, the spring chamber, and the pressure screw of the spring which protrudes through the top of the spring casing (14) are inclosed by a dome or cap (15) which is aerforateol in its top to form an external muffler, threaded at (16) to engage a corresponding threaded por tion on the chamber (5) at a point just below the inner mufiier (12). The upper end of this cap is provided with a centralturret- (17) adapted to inclose the adjusting screw and lock nuts, andperforated in its vertical walls.

18 is a valve provided with a seat surface (19) normally resting on the seat (8) of the casing. The valve is concavo-convex and protrudes through the valve seat, its lower or pressure surface being convex and its upper or exhaust surface concave. It is provided upon its upper or exhaust surface at its edge with a vertically projecting flange (20), which is of an external diameter slightly less than the internal diameter of the cylindrical guide (10). These cylindrical surfaces cooperate to guide the valve in its motion. The valve is provided on its lower surface with a hub guide (21), which enters and reciprocates in the stationary guide (9) which is within the lower section of the casing and on the pressure side of the valve seat. The under side of this valve is marked 22, and as before described, is convex. It might be conical or concave so far as its function is concerned of deflecting the steam and reducing the effect of the impact of the steam upon the valve when escaping. The guiding surfaces (20 and 21) are slightly spaced from the corresponding bearing surfaces of the casing to allow for expanding and contracting of the parts due to variation of temperature. The curve of the under or pressure surface of the valve extends from the seat surface toward the hub, because the effective action of the impact of escaping steam is greatest at or near the periphery of the valve. The top of the valve, as above stated, is concave at 24, and in its center there is formed a depression or cavity (25) which forms a step for the foot (28) of the bearing member (26). The lower surface (27) of the bearing member (26) is convex and is of less radius than the curve of the concavity of the valve, leaving a free clearance space between the valve and the bearing member, while the foot (28) fits into and fills the step (25).

29 is the spring which rests at its lower end upon a recess (30) in the edge of the bearing member (26), and at its upper ed e in a re cess (31) in an upper pressure b ock (32).

The upper end of the spring casing (14) is perforated and provided with an internal thread (33).

(34) is the adjusting screw which is tapped into the thread (33) and provided upon its lower end with a hemispherical surface which fits a socket or step in the upper bearing block (32).

35 is a head upon the upperend of the screw (34) and (36) a lock nut threaded on the screw, and when screwed down bearing upon the top of the spring casing (14) to lock the screw in an adjusted position.

An important feature of the structure lies in the fact that the dome or cap (15) which forms the external mufller covers and incloses the adjusting screw as well as the inner muffler, and when removed for the adjustment of the screw (35) is so large and important a art of the structure that it is not likely to he left ofi by'those in charge of the apparatus. j

Another advantage of this structure is found in the fact that the screw is provided with a large strong head which permits the use of a large wrench and the positive adjustment of the screw with ease. The lock nut is located upon the screw between its head and the top of the spring casing, and is not detached when the spring is adjusted. Hence the danger of its loss is avoided. The lock nut forms no portion of the casing and the diameter of the screw head is not limited to that of the screw and may be made of any desired size and strength.

When the device is in operation the tension of the spring (29) is regulated by means of the screw (34) to yield to a predetermined pressure on the under side of the valve.

W hen this pressure is reached the valve lifts partially closes the spring chamber, so that g the spring is not exposed to the principal 5 part of the escaping steam. Vlhatever steam does enter the spring chamber escapes through the holes in the top of the chamber and through the perforations of the turret (17). The inde endent motion of the valve is maintained y the form' of the spring bearing block, its foot, and the corresponding step in the surface of the valve; and the clogging is prevented by the free clearance between the bearing block and the valve.

The inclined deflecting surface (22) on the pressure side of the valve so controls the effect of the escaping steam upon the valve that less irregularity of pressure and therefore less vibration and chattering of the valve results from this cause.

All of the elements above described cooperate to produce a safety valve which, under the ordinary trying conditions of use, particularly on locomotives, will act promptly and smoothly, will mufile the escaping steam, will not discharge more steam than the setting of the valve is designed to permit, will not chatter and consequently not wear, and will maintain the same efiective and economical operation indefinitely.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In combination with a container for a fluid under pressure having an opening, a valve seat, a plurality of guiding members, one internally and another externally disposed in regard to the container, the valve having a convex surface internally and a concave surface externally disposed, the latter extending through the seat, a bearing member in the concavity mounted to rock freely in relation to the valve and a spring acting through the bearing member to press the valve against the seat.

'2. In combination with a container for a fluid under pressure having an opening, a valve seat adjacent the opening, a plurality of guiding members, one internally and another externally disposed in regard to the container, a valve having a convex surface internally and a concave surface externally disposed, the latter extending through valve opening, a bearing member in the concavity having a convex surface of less radius than the concave surface of the valve, and a spring acting through the bearing member to press the valve against the seat.

In combination with a container for a fluid under pressure having an opening, a valve seat adjacent the opening, a plurality of guiding members, one internally and another externally disposed in regard to the container, a valve having a convex surface internally and a concave surface externally disposed, the latter extending through the valve opening, a bearing member in the conless radius than the concave surface of the valve, mounted in the concavity to rock freely in relation to the valve, so that wedging and cloggirigof the parts by accumulation of rust flakes, or the like, is prevented and a spring acting through the bearing member to press the valve against the seat.

4. In combination with a container for fluid under pressure having an opening, a valve seat adjacent the opening a plurality of guiding members, one internally and another externally disposed in regard to the container, a valve having an outer surface substantially concave and extending through the valve opening, a step in the concave surface, a bearing block in the concavity having a bearing surface substantially convex and of radius less than that of the concavity, a foot on the bearing block engaging the step and a spring acting through the bearing block to press the valve against the seat.

5. In combination with a container for fluid under pressure having an opening and a valve seat adjacent the opening, a plurality of guiding members, one internally and another externally disposed in regard to the container, a valve having an outer surface substantially concave and extending through the valve opening, a deflecting surface on the pressure side of the valve terminating in the neighborhood of the valve opening, a block in the concavity having a bearing surface and of less radius than that of the concavity, and a spring acting through the block to press the valve against the seat.

6. In a safety valve in combination with a casing having a seat and a guide, a valve having a seat surface and guide surface, an inclined deflecting surface extending to a point adjacent the seat, the exhaust side of the valve being depressed to form a broad cavity extending through the seat, a bearing member in the cavity adapted to rock freely in relation to the valve and a spring acting through the bearing member to press the valve against the seat.

7. In a safety valve in combination with a casing having a seat and guides on both the pressure and exhaust sides of the seat, a valve having a seat surface and guide surfaces, an inclined deflecting surface extending from one guide surface to a point adjacent the seat, the exhaust side of the valve being depressed to form a broad cavity ex tending through the seat and having a central step, a bearing member in the cavity engaging the step and adapted to rock freely in relation to the valve and a spring acting through the bearing member to press the valve against the seat.

8. In a safety valve in combination with a casing having a seat and a guide, the valve having a seat surface and a guide surface,

the exhaust side of the valve being depressed I Signed by me at Baltimore, Maryland, this to form a broad ca-Vity extending through I 19th day of February, 1908.

the seat a bearing member in the cavity adapted to rock freely in relation to the HARRY MOOARTY' 5 valve and a spring acting through the beer- Witnesses:

ing member to press the valve against the EDWARD L. BASH,

seat. LESTER H. LATHAM. 

